1. Field of the Invention
The invention relates to a polyphase alternating-current motor that includes bus bars and an electric power steering apparatus.
2. Description of the Related Art
In a polyphase alternating-current motor of the above-mentioned type, each of bus bars the number of which corresponds to the number of phases includes an intermediate electrical path portion, a plurality of end electrical path portions, and a main electrical path portion. The intermediate electrical path portion has a constant width and extends along the circumferential direction of a stator. The end electrical path portions branch from the intermediate electrical path portion at multiple positions in the circumferential direction of the stator. The main electrical path portion is formed at one position of the intermediate electrical path portion. End portions of coils that are wound around respective teeth of the stator are connected to the respective end electrical path portions, and a motor drive circuit is connected to the main electrical path portion (refer to, for example, Japanese Patent Application Publication No. 2003-299287 (JP-A-2003-299287)).
There has been a demand for lighter polyphase alternating-current motors. Therefore, attaining lighter bus bars that are metal components is effective in attaining lighter polyphase alternating-current motors. However, if the width of an intermediate electrical path portion of a bus bar is uniformly reduced so that the width is constant from one end portion to the other end portion of the intermediate electrical path portion, there may arise a problem that a current density becomes excessive in a portion of the intermediate electrical path portion that is close to a main electrical path portion.